According to EP-367326, a cyclohexane hydroperoxide obtained by air oxidation can be converted under a high yield into a corresponding ketone (or ketone, K) and an alcohol (or alkanol, A). In other literature, frequent attention is given to the oxidation of alkanes such as, for instance, cycloalkanes, particularly cyclohexane, to form a corresponding alkanol and/or alkanone. In such methods, two process steps can be distinguished: first of all, the conversion of the alkane into a mixture substantially containing the corresponding alkyl hydroperoxide, followed by a conversion (decomposition) of this alkyl hydroperoxide into a K/A mixture. In addition to the direct conversion of the alkyl hydroperoxide, in this second step the alkyl hydroperoxide frequently also reacts with the substantial amount of remaining alkane, which again results in the formation of K and A. In some cases, this so-called alkane participation plays an essential part in the total conversion of the alkane and the yield of the K/A mixture that goes with it.
The major difference between the oxidation step and the decomposition step is that the latter is performed at lower temperatures. The difference in temperature is at least 20.degree. C., preferably at least 40.degree. C. This may be because in the oxidation step, performed essentially without a catalyst, a relatively high temperature is maintained to keep an acceptable reaction rate; still relatively few products are formed. The decomposition step, in which a substantial amount of catalyst is used, would give rise to many unwanted side products if performed at too high a temperature.
Many catalyst systems have been suggested for use in the above-mentioned process. GB 1212824, for instance, describes a homogeneous catalytic reduction of alkyl hydroperoxides. Homogeneous catalysis for the decomposition of alkyl hydroperoxides is still applied for commercial purposes, in spite of the formation of rather substantial catalyst waste streams. In order to avoid these waste streams, it has been suggested, as in U.S. Pat. No. 2,851,496, to absorb the catalyst on a carrier. However, the activity of such a catalyst has been found in course of time to deteriorate. Nor does the system described in EP-A-367326 (a Co-porphyrin complex, which porphyrin complex is linked with a carrier by means of a covalent bond) provide a stable catalyst active for a long time.